Hydrochlorination of ethylene



United States Patent Oiice 3,247,267 Patented Apr. 1.9, 1966 3,247,267 HYDROCHLORINATION F ETHYLENE David. Brown, lv/Lbrook. Greenwich, Conn., assignor to Halcon International, Ine., a corporation of Delaware 1iiied Nov. 24, 1961. Ser. No. 154,79 2 Claims. (Cl. 260-663) This invention relates to processes for the preparation of ethyl chloride by the hydrochlorination of ethylene in the presence of aluminum chloride catalyst, more particularly to such a process wherein the catalyst is mixed with ethyl chloride and the reaction temperature is controlled by evaporation of ethyl chloride at moderate pressure and a part of the reaction mixture is withdrawn and purged of catalyst, the ethyl chloride therein being recovered or recycled to the reaction mixture, and especially to such a process wherein at least part of the recycled ethyl chloride is processed to remove heavy ends therefrom prior to recycling.

The preparation of ethyl chloride by the hydrochlorination of ethylene in the presence of an aluminum chloride catalyst has achieved commercial success. However, difficulty is encountered in controlling the reaction temperature, and it is undesirable to reduce the pressure in order to keep the temperature of the reaction mixture low enough, c g., down to substantially C. This art is confronted by the problem of providing such a process which operates in an economical and etiicient manner and yet avoids such difculties.

The discoveries associated with the invention and relating to the solution of the above problems, and the objects achieved in accordance with the invention as set forth herein include the provision of:

A process for the preparation of ethyl chloride by the reaction of HC1 and ethylene in the presence of a liquid mixture of ethyl chloride and an aluminum chloride catalyst wherein the reaction temperature is controlled by vaporization of ethyl chloride, including the improvement which comprises removing a small portion of the reaction mixture, vaporizing ethyl chloride from this removed portion, and recovering it or removing at least a part of higher boiling materials from this vaporized crude ethyl chloride, liquifying the ethyl chloride and returning at least a portion of it to the reactor;

Such a -process wherein the spent catalyst in the material removed from the reactor is heated to recover vaporizable material, and then removed from the system;

Such a process wherein the reaction` is conducted at substantially atmopsheric pressure and at approximately the atmospheric boiling temperature of ethyl chloride;

Such a process wherein the amount of material drawn off from the reactor is in the range of about l to 10% by weight of the fresh feed rate;

Such a process wherein the draw-off is intermittent and the ethyl chloride is removed from the draw-olf intermittently;

Such a process wherein the draw-off is continuous and ethyl chloride is removed therefrom continuously; and

Other objects which will be apparent as details or embodiments of the invention are set Iforth hereinafter.

The accompanying drawing is a schematic ow diagram of one embodiment of the invention.

ln order to indicate still more fully the nature of the present invention, the following examples of typical procedures are set forth in which parts and percents mean parts and percents by weights, respectively unless otherwise indicated, it being understood that these examples are presented as illustrative only and they are not intended to limit the scope of the invention.

Example 1 ln this example, the reaction mixture is purged of spent catalyst and also of undesirable high boiling materials by bleeding or drawing olf an amount of the reaction mixture equal to about l to about 10% by volume of the fresh feed rate. This may be done intermittently or continuously, preferably the latter with vaporization `of the ethyl chloride and recovering it or recycling to the reaction mixture after removing at least a part of the heavy ends therefrom. After the process has been continued for suicient time to ybuild up spent catalyst and other heavy ends in the boil-off kettle, the latter is drained and then the process is continued. lf desired the kettle may be heated to boil-off vaporizabie materials prior to draining.

This procedure is described in detail in the following description of the overall process.

Referring to the accompanying drawing, the reactor 1t) is charged with liquid ethyl chloride and aluminum chloride catalyst and maintained at about atmospheric pressure and at approximately the boiling point of ethyl chloride. Ethylene is fed thereinto via line 12 and HCl is fed via line 1l.

The reaction is autotherrnic, all heat being removed by the evaporation of ethyl chloride which passes via line 17 through refrigerated condenser 1S and then via line 17 to knock-out vessel 19 where crude liquid ethyl chloride is separated from the unreacted HCl and ethylene vapor. These unreacted materials are passed via line 75 to compressor 76 wherein they are compressed and then passed via line 77 to refrigerated condenser 78 and the resulting condensed mixture is passed via line 77 to knock-out vessel '79. The vapors separated therein are passed via lines 89 and i6 to reactor lil, a part thereof being vented via line Si) to prevent build-up of non-condensible gases in the system.

More crude ethyl chloride is vaporized in the reactor than is made therein, and accordingly liquid ethyl chloride must be supplied to the reactor to maintain the liquid level. Initially this is supplied via line 26a, pump 2l and lines 22 and 23 or 24.

The net crude liquid ethyl chloride is passed from vessel 19 via line 2h, pump 21 and line 22 to heavy ends column 4t), and a part thereof may be passed via line 23 or line 24 back to the reactor l0 if desired. The vapors from column 4t? are passed via line 41 to condenser 42 and the condensed mixture is passed via line 43 to separator 44. The vapors separated in the latter are passed via lines 74 and 73` to refrigerated condenser 18. The liquid is passed from separator 44 via line 45, pump 46 and line 47 to the light ends column 55. The bottoms fraction from column 49 is passed to line 49, pump 50 and line 5l from which heavy ends are removed. A part thereof is passed via line 52 to reboiler 53 wherein it is heated and then via line 54 back to column 4t).

The ethyl chloride is separated as a bottoms fraction in columns 55' and it is Withdrawn via line 64. It may be withdrawn from the system thereby, by a side line (not shown), but preferably is passed to reboiler wherein it is heated and a part thereof is then passed via line 66 back to lcolumn S5. A part of the reheated mixture is passed to knock-out vessel 68. The liquid separated therein is passed via line 68h back to reboiler 65. The separated vapor is passed from vessel 68 via line 68a to condenser 69 and the resulting liquid is the ethyl chloride product which is withdrawn via line 76.

As set forth more fully in a companion application filed herewith, the condenser and draw-off lines are made of alloy so as to provide a product which is not contaminated by iron. A portion of the material may be passed from reboiler 65 via line 71 back to the reactor. This material contains only traces of heavy ends or highboilers.

The vapor from column 55 is passed via line 56 to condenser 57 and the resulting mixture is passed via line 58 to separator 59. The liquid separated therein is passed via line 60, pump 61 to light ends withdrawal line 63. A part of the'light ends fraction is passed via linev 61 to column 55, as reux. The vapor separated in separator 59 is passed via line 73 to refrigerated condenser 18.

A part of the reaction mixture (1 to 10% based on fresh feed) is passed from reactor 10 via line 25, pump l27, yline 26 to kettle 27. This kettle is provided with heating means (not shown) and agitating means such as a shaft 30 provided with propeller blades 31 and a motor 29. The mixture is heated in this kettle and vaporized ethyl Achloride is passed via line 33 to condenser 35 and the resulting mixture is passed via line 35a to vessel or separator 36. Any gas separated therein may be vented via line 36a. Alternativelyrthe gas (from line 36a) may be returned to refrigerated condenser 18 (connection not shown). Liquid is passed from separator 36 via line 37, pump 38 and lines 39 and 22 to heavy ends column 40, for processing as already described. v

If desired part of the vapors from kettle 28 may be passed via lines 33 and 34 to refrigerated condenser 18, wherein they are processed as already described. y Additional aluminum chloride may be added as needed via line Y13, hopper 14 and valve 15.

The spent catalyst is accumulated in kettle 28 until the kettleis substantially lled. Then the process is stopped, the kettle heated to remove vaporizable material which may be withdrawn (or processed in the system described) and then the kettle is drained, spent catalyst being removed via line 28a.

In this way, the reactor is substantially continuously purged of spent catalyst and heavy ends and the ethyl chloride which is removed with the purge is recovered or processed to remove at least a part of the heavy ends therein prior to recycling, whereby the reaction temperature is not unduly raised due to the presence of undesirable amounts of high-boilers in the reaction mixture.

Comparable results to the foregoing are achieved with various modications thereof, including the following. The recovery of ethyl chloride may be carried out in any convenient manner although the system described above, removing the heavy ends rst as bottoms and then removing the ethyl chloride in a separate column as a bottoms fraction is preferred, since this enables one to produce a product of extremely low HC1 content. The gaseous vapors separated in the knock-out vessels or separators may be processed in any convenient manner. However, the above described procedure of recycling the gaseous materials back to the reactor is preferred in order to obtain higher yield based on ethylene or HCl or both, as well as help control the reaction temperature in the reactor, as set forth more fully` in a companion application led herewith. The known reaction conditions, catalyst concentration and reactant proportions are applicable in the present process.

The smooth and efficient operation of the process with high yield and adequate reaction temperature control achieved in accordance with the invention are indeed surprising, especially when one considers the long time that this problem has baled those skilled in this art.

In View of the foregoing disclosures, variations and modiiications thereof will be apparent to one skilled in the art,.and it is intended to include within the invention all such variations and modifications except as do not come within the scope of the` appended claims.

What is claimed is: f

1. In a process for the preparation of ethyl chloride wherein hydrogen chloride and ethylene are reacted in a reaction zone in the presence of a liquid mixture of an aluminum chloride catalyst in ethyl chloride, wherein the reaction temperature is controlled by the vaporization kof ethyl chloride from said reaction zone, and wherein the bulk of the e-thyl chloride is removedfrorn the reaction zone as a vapor, the improvement of: withdrawing from l to 10% by weight (based on weight of ethylene and hydrogen chloride) of the reaction mixture as the liquid from said reaction zone, said reaction mixture containing ethyl chloride, heavy ends, and catalyst; heating said withdrawn liquid to vaporize said ethyl chloride and heavy ends; separating said vapors from said catalyst; separating said heavy ends from said ethyl chloride; liquifying said ethyl chloride and recycling at least a portion thereof to said reaction zone.

2. The 'process of claim 1 wherein the reaction tem# perature is kept down to substantially 10 C.

References Cited by the Examiner UNITED STATES PATENTS LEON ZITVER, Primary Examiner. ALPHoNso D. SULLIVAN, Examiner. 

1. IN A PROCESS FOR THE PREPARATION OF ETHYL CHLORIDE WHEREIN HYDROGEN CHLORIDE AND ETHYLENE ARE REACTED IN A REACTION ZONE IN THE PRESENCT OF A LIQUID MIXTURE OF AN ALUMINUM CHLORIDE CATALYSST IN ETHYL CHLORIDE, WHEREIN THE REACTION TEMPERATURE IS CONTROLLED BY THE VAPORIZATION OF ETHYL CHLORIDE FROM SAID REACTION ZONE, AND WHEREIN THE BULK OF THE ETHYL CHLORIDE IS REMOVED FROM THE REACTION ZONE AS A VAPOR, THE IMPROVEMENT OF: WITHDRAWING FROM 1 TO 10% BY WEIGHT (BASED ON WEIGHT OF ETHYLENE AND HYDROGEN CHLORIDE) OF THE REACTION MIXTURE AS THE LIQUID FROM SAID REACTION ZONE, SAID REACTION MIXTURE CONTAINING ETHYL CHLORIDE, HEAVY ENDS, AND CATALYST; HEATING SAID WITHDRAWN LIQUID TO VAPORIZE SAID ETHYL CHLORIDE AND HEAVY ENDS; SEPARATING SAID VAPORS FROM SAID CATALYST; SEPARATING SAID HEAVY ENDS FROM SAID ETHYL CHLORIDE; LIQUIFYING SAID ETHYL CHLORIDE AND RECYCLING AT ELAST A PORTION THEREOF TO SAID REACTION ZONE. 